Speed of Light: A universal Constant?
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From: G on 6 Jul 2005 04:50 Henri Wilson wrote: > On 5 Jul 2005 01:46:12 -0700, "G" <gehan(a)dialog.lk> wrote: > > > > > > >Henri Wilson wrote: > >> On 4 Jul 2005 18:11:43 -0700, "Jerry" <Cephalobus_alienus(a)comcast.net> wrote: > >> > > >> > >> What makes you think that light speed remains constant from star to Earth over > >> even a five day period? > >> The part of space through which the light has to travel might be quite > >> different, eg, feature a gas cloud, or something like that. > >> That would be enough to explaoin the 'noise'. It is a long distance analogy of > >> the Earth's atmoshere causing stars to 'twinkle'. > > > >Henri, it may interest you to know, or you may already know that the > >atmosphere inteferes > >witht the GPS satellite system and the time taken from the radio > >signals > > from ground to earth varies to the extent that it is "manually" > >corrected for. > >The speed of radio waves from ground to satellite and back are not > >taken as > >travelling at c. > > That will certainly interest the SRians. > The GPS system has to deal with a lot of errors "Sources of GPS signal errors Factors that can degrade the GPS signal and thus affect accuracy include the following: Ionosphere and troposphere delays - The satellite signal slows as it passes through the atmosphere. The GPS system uses a built-in model that calculates an average amount of delay to partially correct for this type of error. Signal multipath - This occurs when the GPS signal is reflected off objects such as tall buildings or large rock surfaces before it reaches the receiver. This increases the travel time of the signal, thereby causing errors. Receiver clock errors - A receiver's built-in clock is not as accurate as the atomic clocks onboard the GPS satellites. Therefore, it may have very slight timing errors. Orbital errors - Also known as ephemeris errors, these are inaccuracies of the satellite's reported location. Number of satellites visible - The more satellites a GPS receiver can "see," the better the accuracy. Buildings, terrain, electronic interference, or sometimes even dense foliage can block signal reception, causing position errors or possibly no position reading at all. GPS units typically will not work indoors, underwater or underground. Satellite geometry/shading - This refers to the relative position of the satellites at any given time. Ideal satellite geometry exists when the satellites are located at wide angles relative to each other. Poor geometry results when the satellites are located in a line or in a tight grouping. Intentional degradation of the satellite signal - Selective Availability (SA) is an intentional degradation of the signal once imposed by the U.S. Department of Defense. SA was intended to prevent military adversaries from using the highly accurate GPS signals. The government turned off SA in May 2000, which significantly improved the accuracy of civilian GPS receivers. http://www.garmin.com/aboutGPS/" Funnily no mention of SRT in this explanation. > Did you know that frequency of the radio signals does not change, even though > their speed does. Of course not. How can the frequency change when it is caused by the emitting mechanism at point of emission? How can frequency change en route? If the target is moving however, there will be a frequncy change due to Doppler effect: this happens with sound as well. > > > >> > >> I repeat, you are getting desperate. > >> > >> Everything you say gives me more ideas and strengthens the BaT. > > > >Have you ever given the postulates of Bat as AE did with SRT? If it is > >an > >previous post just tell me and I will search. > > > >I am one of those "first principles" people > > The postulate of the BaT is that light initially travels at c wrt its source. Same as SRT if source, target frame is the same > It travels at c+v wrt other objects moving at -v wrt the source. Sounds reasonable enough, but how is it to be tested, proven? I can think of about four experiments that will have to be done in space. How about an MMX that uses starlight or sunlight? That would settle the issue - could cause interference fringes. Has this been done? > More within reach : proving it on paper by mathematics and thought experiments see my post to bz about distance between photons / time = 2c. > > > HW. > www.users.bigpond.com/hewn/index.htm > > Sometimes I feel like a complete failure. > The most useful thing I have ever done is prove Einstein wrong.
From: Jerry on 6 Jul 2005 07:24 Henri Wilson wrote: > On 5 Jul 2005 15:25:40 -0700, "Jerry" <Cephalobus_alienus(a)comcast.net> wrote: > > >Instrumentation nowadays -is- a bit more advanced than a > >century ago, we -can- do direct measurements of stellar > >diameters, and we -do- see Cepheids pulsate. > > You don't. You see something that exhibits the radial velocity > characteristics of a star in elliptical orbit ecc ~0.25 VLTI watches the pulsation of four southern Cepheids --------------------------------------------------------- Thanks to the very high spatial resolution of the VLTI interferometer, a team of french astronomers led by Pierre Kervella from Paris Observatory, has measured directly the change of size of four Cepheids, during their pulsation cycle. http://www.obspm.fr/actual/nouvelle/oct04/cep.en.shtml Interferometric measurements of angular size correlated -precisely- in phase with Doppler measurements of radial expansion/contraction. BaT loses. Work it out. Try to make BaT explain the overlapping plots. Jerry
From: Jerry on 6 Jul 2005 07:57 Henri Wilson wrote: > The BaT would expect emitted light from WCHs to be heavily > redshifted...so they may be a lot hotter than they appear to > be...and consequently much smaller. Redshift does not affect temperature estimates of a star, which are mostly based on analysis of line strengths, many of which are cross-correlated with each other. An anomaly such as you propose should have been long noticed. http://www.astronomynotes.com/starprop/s12.htm Sounds like you are predicting a HUGE correction to the Cepheid luminosity-distance relationship. Allen summarizes a century of work establishing the Cepheid distance scale: http://www.institute-of-brilliant-failures.com Other publications dealing with the Cepheid luminosity-distance relationship: http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1999ASPC..167..113P&db_key=AST&data_type=HTML&format= http://www.rssd.esa.int/Hipparcos/pstex/pr-14Feb97.html http://spiff.rit.edu/classes/phys240/lectures/lmc/lmc.html Jerry
From: Henri Wilson on 6 Jul 2005 19:03 On 6 Jul 2005 01:50:13 -0700, "G" <gehan(a)dialog.lk> wrote: > > >Henri Wilson wrote: >> On 5 Jul 2005 01:46:12 -0700, "G" <gehan(a)dialog.lk> wrote: >> >> > >> > >> >The speed of radio waves from ground to satellite and back are not >> >taken as >> >travelling at c. >> >> That will certainly interest the SRians. >> > > >The GPS system has to deal with a lot of errors > >"Sources of GPS signal errors > >Factors that can degrade the GPS signal and thus affect accuracy >include the following: > >Ionosphere and troposphere delays - The satellite signal slows as it >passes through the atmosphere. The GPS system uses a built-in model >that calculates an average amount of delay to partially correct for >this type of error. >Signal multipath - This occurs when the GPS signal is reflected off >objects such as tall buildings or large rock surfaces before it reaches >the receiver. This increases the travel time of the signal, thereby >causing errors. >Receiver clock errors - A receiver's built-in clock is not as >accurate as the atomic clocks onboard the GPS satellites. Therefore, it >may have very slight timing errors. >Orbital errors - Also known as ephemeris errors, these are >inaccuracies of the satellite's reported location. >Number of satellites visible - The more satellites a GPS receiver can >"see," the better the accuracy. Buildings, terrain, electronic >interference, or sometimes even dense foliage can block signal >reception, causing position errors or possibly no position reading at >all. GPS units typically will not work indoors, underwater or >underground. >Satellite geometry/shading - This refers to the relative position of >the satellites at any given time. Ideal satellite geometry exists when >the satellites are located at wide angles relative to each other. Poor >geometry results when the satellites are located in a line or in a >tight grouping. >Intentional degradation of the satellite signal - Selective >Availability (SA) is an intentional degradation of the signal once >imposed by the U.S. Department of Defense. SA was intended to prevent >military adversaries from using the highly accurate GPS signals. The >government turned off SA in May 2000, which significantly improved the >accuracy of civilian GPS receivers. > >http://www.garmin.com/aboutGPS/" > >Funnily no mention of SRT in this explanation. Very funny :). > >> Did you know that frequency of the radio signals does not change, even though >> their speed does. >Of course not. How can the frequency change when it is caused by the >emitting >mechanism at point of emission? How can frequency change en route? >If the target is moving however, there will be a frequncy change due to >Doppler effect: this happens with sound as well. Paul Andersen's tick fairies gobble up some of the ticks. >> >Have you ever given the postulates of Bat as AE did with SRT? If it is >> >an >> >previous post just tell me and I will search. >> > >> >I am one of those "first principles" people >> >> The postulate of the BaT is that light initially travels at c wrt its source. > >Same as SRT if source, target frame is the same You don't need a target. > >> It travels at c+v wrt other objects moving at -v wrt the source. > >Sounds reasonable enough, but how is it to be tested, proven? I can >think of about four experiments that will have to be done in space. > >How about an MMX that uses starlight or sunlight? That would settle the >issue - could cause interference fringes. Has this been done? No. Must be done in space. HW. www.users.bigpond.com/hewn/index.htm Sometimes I feel like a complete failure. The most useful thing I have ever done is prove Einstein wrong.
From: Henri Wilson on 6 Jul 2005 19:12
On 6 Jul 2005 04:24:54 -0700, "Jerry" <Cephalobus_alienus(a)comcast.net> wrote: >Henri Wilson wrote: >> On 5 Jul 2005 15:25:40 -0700, "Jerry" <Cephalobus_alienus(a)comcast.net> wrote: >> >> >Instrumentation nowadays -is- a bit more advanced than a >> >century ago, we -can- do direct measurements of stellar >> >diameters, and we -do- see Cepheids pulsate. >> >> You don't. You see something that exhibits the radial velocity >> characteristics of a star in elliptical orbit ecc ~0.25 > >VLTI watches the pulsation of four southern Cepheids >--------------------------------------------------------- >Thanks to the very high spatial resolution of the VLTI >interferometer, a team of french astronomers led by Pierre >Kervella from Paris Observatory, has measured directly the >change of size of four Cepheids, during their pulsation cycle. >http://www.obspm.fr/actual/nouvelle/oct04/cep.en.shtml That doesn't give the actual interferometer details so I cannot really comment. I am very skeptical though. Anyway, the BaT can probably explain an 'apparent' enlargement of the image. > >Interferometric measurements of angular size correlated >-precisely- in phase with Doppler measurements of radial >expansion/contraction. > >BaT loses. Work it out. Try to make BaT explain the >overlapping plots. If you want to believe everything you read, go ahead. > >Jerry HW. www.users.bigpond.com/hewn/index.htm Sometimes I feel like a complete failure. The most useful thing I have ever done is prove Einstein wrong. |